This is nylon obtained by the polymerisation of hexamethylenediamine and adipic acid. It's one of the oldest engineering plastics, having been created in the USA in 1930. Due to its origin it's widely used in the American and English markets. In comparison to nylon 6 it's stiffer and tougher but more brittle. It's advisable to use PA66 instead of PA6, when a higher stiffness is required to the detriment of resilience. It can be easily machined on automatic machine tools.
• Wear resistance: it is good even in demanding environments.
• Self-lubricating: the friction coefficient is low and generally for sliding application it does not require lubricators.
• Toughness: very high tensile stress and compressive strength. Its toughness is higher than that of Polyamide 6.
• Machining on automatic machine tools is shown to be easy as the shavings break thanks to its higher toughness.
• Ageing resistance and weatherproof.
• It's resistant to alkali, inorganic compounds and solvents.
• In some cases it can be used in contact with food.
• It is hygroscopic, even if to a lesser extent than PA6.
• It absorbs moisture in time and consequently the mechanical features and the final dimensions will change.
• Use in the electrical field is to be avoided as the electrical features change with the moisture content.
Due to its higher stiffness than PA6, it’s used for mechanical applications when this feature is more important than that of shock resistance, particularly suitable for:
• Anti-wear guides.